By default the Kindle is in in debug mode. I’m running Mac OS X Lion and I wanted to get adb to recognize the Amazon Kindle. I’ve added the following to ~/.android/adb_usb.ini
# run this command to add 0x1949 to the adb_usb.ini file
$ echo 0x1949 >> ~/.android/adb_usb.ini
You’ll need to kill adb if it’s running and restart it.
adb kill-server
adb start-server
Also you might as well reboot your kindle and plug in the usb cable. After that you should see the kindle when running adb devices
$ adb devices
320A40610000009 device
This should make the Kindle much more reliable with adb, before this change adb would recognize the Kindle about 50% of the time.